/*
 * Copyright 2019 ZetaSQL Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package com.google.zetasql;

import io.grpc.Channel;
import java.util.ServiceLoader;

/** Provides a interface for accessing the client channel. */
public interface ClientChannelProvider {

  /** Returns the channel to ZetaSQL server. */
  Channel getChannel();

  /** Returns the channel to ZetaSQL server from a Service implementation. */
  static Channel loadChannel() {
    for (ClientChannelProvider provider : ServiceLoader.load(ClientChannelProvider.class)) {
      return provider.getChannel();
    }
    throw new IllegalStateException("No ZetaSQL ClientChannelProvider loaded.");
  }
}
